1. Technical Field
This invention is related to the field of high-speed interface design, and more particularly to AC coupling techniques.
2. Description of the Related Art
Computing systems typically include a number of interconnected integrated circuits. In some cases, the integrated circuits may communicate through parallel interfaces, which simultaneously communicate multiple bits of data. In other cases, the integrated circuits may employ a serial interface, which sequentially communicates one bit of data at a time. For both parallel and serial interfaces, communicated data may be differentially encoded.
In a computing system, the integrated circuits may have different power supply requirements, which may result in different output voltages being coupled to the integrated circuits' respective communication ports. Furthermore, variations in the properties of wiring traces on circuit boards as well as differences in power supply performance, may further contribute to differences in the power supply voltages supplied to the integrated circuits.
In some cases, each integrated circuit may be coupled to an interface through a series capacitor to remove the DC component of a transmitted or received signal, allowing only the high frequency portion of the transmitted or received signal to pass. During power-up, it may be necessary to charge the series capacitor to a voltage level sufficient to transceiver circuits to operate properly.